Treatment of thromboembolism in cancer patients

Coagulation and cancer: biological and clinical aspects

Malignancy affects the hemostatic system and the hemostatic system affects malignancy. In cancer patients there are a number of coagulation abnormalities which provide the background for an increased tendency of these patients to both thrombosis and hemorrhage. The causes of this coagulation impairment rely on general risk factors which are common to other categories of patients, and other factors which are specific to cancer, such as tumor type and disease stage. In addition, data from basic research indicate that the hemostatic components and the cancer biology are interconnected in multiple ways. Notably, while cancer cells are able to activate the coagulation system, the hemostatic factors play a role in tumor progression. This opens the way to the development of bifunctional therapeutic approaches that are both capable of attacking the malignant process and resolving the coagulation impairment. On the other hand, the management of thrombosis and hemorrhages in cancer patients can be different. To approach these problems, some guidelines have been released by prominent international scientific societies. Also actively investigated is the issue of identifying new biomarkers to classify the subjects at a higher risk, thus improving the prevention of thrombohemorrhagic events in these patients. Finally, novel prophylactic and therapeutic approaches are currently under development. This review provides an overview of the hemostatic complications in cancer, together with new insights into the interaction between hemostasis and cancer biology. We also review the assessment of the risk of thrombohemorrhagic events in cancer patients, and the prophylaxis and treatment of such manifestations.

Hemostatic factors, innate immunity and malignancy

Genetics-based studies have established the critical importance of tumor cell-associated tissue factor, circulating and endothelial cell-associated regulators of thrombin function and multiple thrombin substrates in metastasis. There appear to be multiple pathways by which procoagulants influence tumor biology, but the capacity of hemostatic factors to regulate innate immune function is at least one emerging theme. Several reports have shown that the platelet/fibrin(ogen) axis supports metastasis by limiting natural killer cellmediated lysis of newly-localized micrometastases. Furthermore, there is increasingly compelling evidence that hemostatic and innate immune system interactions also support very early events in cancer development. Analyses of the role of fibrin(ogen) in inflammation-driven colon cancer established a major role for this provisional matrix protein in early tumor development. A seminal property of fibrin(ogen) driving tumor formation in this context is the capacity to support local leukocyte activation events through engagement of the leukocyte integrin α(M)β(2). More recent studies have also suggested that hemostatic factors can, in at least some settings, program the malignant phenotype in tumor cells. Platelet-derived TGF-β1 and other platelet products were reported to trigger a more invasive and prometastatic epithelial-mesenchymal-like transition in embolic tumor cells. These findings support the intriguing concept that tumor cell functional properties can continue to evolve, even beyond the primary tumor site, in response to tumor cell-hemostatic factor interactions in the bloodstream. Taken together, there is strong evidence that the hemostatic system plays a multifaceted role in cancer pathogenesis and that therapies targeting selected hemostatic factors may present a powerful means to impede tumor development and metastasis.

Gc protein-derived macrophage-activating factor (GcMAF) stimulates cAMP formation in human mononuclear cells and inhibits angiogenesis in chick embryo chorionallantoic membrane assay

The effects of Gc protein-derived macrophage-activating factor (GcMAF) have been studied in cancer and other conditions where angiogenesis is deregulated. In this study, we demonstrate for the first time that the mitogenic response of human peripheral blood mononuclear cells (PBMCs) to GcMAF was associated with 3'-5'-cyclic adenosine monophosphate (cAMP) formation. The effect was dose dependent, and maximal stimulation was achieved using 0.1 ng/ml. Heparin inhibited the stimulatory effect of GcMAF on PBMCs. In addition, we demonstrate that GcMAF (1 ng/ml) inhibited prostaglandin E(1)- and human breast cancer cell-stimulated angiogenesis in chick embryo chorionallantoic membrane (CAM) assay. Finally, we tested different GcMAF preparations on CAM, and the assay proved to be a reliable, reproducible and inexpensive method to determine the relative potencies of different preparations and their stability; we observed that storage at room temperature for 15 days decreased GcMAF potency by about 50%. These data could prove useful for upcoming clinical trials on GcMAF.

The value of blood D-dimer test in the diagnosis of walk-in patients with venous thromboembolism

Venous thromboembolism (VTE) and related pulmonary thromboembolism are life-threatening diseases that require efficient diagnosis and clinical management. While the diagnosis and treatment of VTE in hospitalized patients has been extensively studied, less has been reported on walk-in patients with VTE. Here we report on four outpatients with VTE that were efficiently diagnosed using the blood D-dimer test and successfully treated.

Approach to venous thromboembolism in the cancer patient

OPINION STATEMENT

Venous thromboembolism (VTE) is frequently encountered in cancer patients, acts as an important cause of morbidity and mortality, and may be a predictor of worse prognosis. In cancer patient who have a poor life expectancy, preventing death from pulmonary embolism is the mainstay of treatment. Patients who present with severe hypotension or other clinical manifestations suggestive of critical pulmonary embolism and do not have contraindications to thrombolysis should promptly be administered thrombolytic drugs. Except for selected cases requiring aggressive therapy, treatment of VTE in patients with cancer should not differ from that of patients without malignancy; the initial treatment should be conducted with adjusted dose of unfractionated heparin (UH), fixed dose of low-molecular-weight heparins (LMWH), or fondaparinux. LMWHs and fondaparinux have the potential to greatly simplify the initial treatment of VTE, making the management of the pathology feasible in an outpatient setting for selected patients. Traditionally, in cancer as well as in non-cancer patients, UH or LMWH or fondaparinux are overlapped by oral anticoagulation, targeted to reach an International Normalized Ratio (INR) between 2.0 and 3.0, and then followed by oral anticoagulants. However, during oral anticoagulant therapy, cancer patients exhibit a two- to fourfold higher risk of recurrent VTE and major bleeding complications when compared to non-cancer patients. Studies performed during the current decade have demonstrated that LMWHs offer several advantages in terms of efficacy in preventing VTE recurrences without increasing the bleeding risk. According to International Guidelines, the long-term administration of LMWH should be considered an alternative to anti-vitamin K drugs in patients with advanced disease and in those with conditions limiting the use of oral anticoagulants. The targeted policy is to administer LMWH at full therapeutic doses for the first month of treatment and then 75% of the initial dose for at least the following 5 months of therapy. Prolongation of anticoagulation should be considered for as long as the malignant disorder is active. In patients with acute deep venous thrombosis and contraindications to anticoagulation, vena cava filters should be considered. If anticoagulation is temporarily contraindicated, retrievable filters should be considered. Only patients who are actively bleeding or who are at extremely high risk for bleeding should receive a filter without anticoagulation coverage.